1. Field of the Invention.
This invention relates to apparatus for medical test procedures and, more particularly, to a disposable one-piece centrifuge tube with a separable dispenser receptacle at the end of the centrifuge tube.
2. Description of the Related Art.
In medical diagnostic laboratory tests it is often desirable to centrifuge a liquid sample and examine with a microscope the heavier material which separates out under centrifugation. Urinalysis and hemanalysis are two examples of typical diagnostic tests in which such a procedure is desirable. Other processes of medical and biological research also require the separation of heavier components from a liquid by centrifugation. In many cases the final step of an analytical procedure involves examining the separated components on a slide under a microscope, sometimes after staining or some other type of treatment. It would be an extremely useful development in the art of microscopic examination of the sediment resulting from centrifugation of a liquid sample if there were available a convenient, disposable device in which the centrifuging of the sample can take place and which allows the resulting sediment to be conveniently manipulated and dispensed onto a microscope slide for specimen preparation and subsequent examination.
The standard technique of first mixing the sediment with some supernatant liquid to facilitate the transferral to a microscope slide and then pipetting the mixed sediment to the slide is overly time-consuming. Furthermore, the mixing and transferring steps make use of three different pieces of equipment in contact with the sediment (the centrifuge tube, the pipet, and the microscope slide), increasing the possibility of specimen contamination prior to examination.
One approach to the problem has been to design a combination centrifuge tube and microscope slide device which eliminates the need for a separate decanting of the sediment from a specimen after it has been centrifuged to collect the sediment. U.S. Pat. No. 4,066,414 to Selby discloses a one-piece tube and microscope slide device for use in clinical procedures employing a liquid test specimen. A normally upright tubular reservoir structurally equivalent to an ordinary test tube has a microscope slide chamber frangibly connected to its lower end. The slide chamber comprises closely spaced opposed planar walls of optically transparent material. A transition member between the tubular reservoir and the slide chamber has a bore to allow flow communication between the reservoir and the slide chamber. The device functions initially as a test tube to allow chemical analysis or specific gravity measurements to be initially made, and thereafter as a microscope slide after centrifugation and frangible detachment of the slide chamber from the reservoir tube.
U.S Pat. No. 3,814,522 to Clark et al is directed to a specimen tube open at its upper end and suitable for use in a centrifuge having a closed lower end which is flattened to define a reduced chamber portion for retaining a thin layer of sample for microscopic examination of the sediment within the flattened portion. The main body portion of the tube has a flat surface extending along a plane parallel with the flattened lower end portion of the tube.
U.S. Pat. No. 3,750,645 to Bennett et al is directed to a separator tube for separating serum or plasma from the cells in blood. A constriction divides the tube into two chambers and has an inside diameter sufficient to allow serum or plasma to pass but not so large as to prevent the formation of an "air lock" between the chambers when the tube containing the blood is held horizontally. After separation of the cells from the serum or plasma by settling or centrifugation, the tube is fractured at the constriction into two containers, one with only serum or plasma and the other with only cells. The container holding the serum or plasma can be closed with a stopper, cap, or sealing material and provided with various features to facilitate dispensing of the fluid portion.
U.S. Pat. No. 3,914,985 to von Behrens is directed to a device and method for harvesting, compacting, and measuring particulate matter suspended in liquids such as body fluids. The device comprises an outer tube closed at its lower end and containing a removable inner tube, the inner tube having an upper section defining an enlarged chamber and having a transparent lower section provided with a capillary passage communicating with the chamber. After particulate matter has collected in the capillary passage by centrifugation, the inner tube is removed and the lower capillary section is separated and is thereafter re-centrifuged at higher speed to compact the particulate matter for optical volumetric measurement. In one embodiment the lower end of the capillary tube is open and communicates directly with the interior of the outer tube so that during initial centrifugation an equilibrating flow of liquid and particulates takes place to displace from the inner tube substantially all but the uppermost strata of particulates.
Neither of the two devices disclosed by Clark et al and by Selby allows any type of treatment of the sediment produced in centrifugation before analysis under a microscope. Neither the blood separation methods disclosed by Bennett et al nor the device and method for harvesting, compacting, and measuring particulate matter disclosed by von Behrens provides a simple and convenient device and method for dispensing the heavier separated components of a centrifuged liquid sample without requiring additional components and manipulative steps. It would be a significant advance in clinical and research laboratory procedures if there were developed a unitary centrifuge tube having a smaller container at its lower end which could be separated from the main part of the tube and conveniently manipulated to dispense the enclosed sediment onto one or more microscope slides or into one or more test tubes for subsequent microscopic or chemical analysis.